CN115845893B - Method for in-situ construction of metal-doped two-dimensional carbon nitride nano sheet/carbon nano tube multi-stage structure and product thereof - Google Patents

Method for in-situ construction of metal-doped two-dimensional carbon nitride nano sheet/carbon nano tube multi-stage structure and product thereof Download PDF

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CN115845893B
CN115845893B CN202211257820.XA CN202211257820A CN115845893B CN 115845893 B CN115845893 B CN 115845893B CN 202211257820 A CN202211257820 A CN 202211257820A CN 115845893 B CN115845893 B CN 115845893B
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程思
江伟辉
江峰
刘健敏
冯果
苗立峰
包镇红
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Jingdezhen Ceramic Institute
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Abstract

The invention provides a method for preparing a metal-doped two-dimensional carbon nitride nano sheet/carbon nano tube multi-stage structure by utilizing a catalytic cracking technology and a product thereof. Firstly, one or more of melamine, melamine hydrobromide, caged phosphate melamine salt and melamine cyanurate are subjected to heat treatment to obtain bulk carbon nitride, the synthesized powder is subjected to continuous thermal etching twice to obtain two-dimensional carbon nitride nano-sheets, the nano-sheets are uniformly mixed with water or ethanol solution of ferric salt, nickel salt or cobalt salt with a certain concentration, then the mixture is dried, and then the mixture is placed in an atmosphere furnace for reduction and catalytic pyrolysis to obtain the metal-doped two-dimensional carbon nitride nano-sheet/carbon nano-tube multi-stage structure. Different from the common composite material of carbon nitride and carbon nano tube through mechanical mixing, the metal doped carbon nitride nano sheet/carbon nano tube obtained by the invention has obvious multi-stage structural characteristics, namely, the highly oriented one-dimensional carbon nano tube is generated on the surface of the metal doped two-dimensional carbon nitride nano sheet in situ.

Description

Method for in-situ construction of metal-doped two-dimensional carbon nitride nano sheet/carbon nano tube multi-stage structure and product thereof
Technical Field
The invention belongs to the technical field of inorganic material preparation, and particularly relates to a method for in-situ construction of a metal-doped two-dimensional carbon nitride nano sheet/carbon nano tube multi-stage structure and a product thereof.
Background
Energy is the basic power for socioeconomic operation and development, but industrial and social development over the past hundred years consumes a large amount of non-renewable fossil fuels such as coal, petroleum, natural gas and the like, emits a large amount of greenhouse gases such as carbon dioxide, sulfur dioxide, nitric oxide and the like and toxic gases, and causes the energy to be increasingly exhausted and the environment to be continuously deteriorated, so that people face serious survival challenges. Solar energy is used as a natural energy source with rich reserves and green and renewable properties, and the research and development of technical means for efficiently utilizing solar energy is one of the main directions of the development of human energy sources at present. The semiconductor photocatalysis technology can convert low-density and dispersed solar energy into high-density and high-concentration chemical energy or directly degrade organic pollutants through sunlight driving a series of important chemical reactions, and is widely focused by researchers at home and abroad. Among them, the key of the photocatalysis technology is to develop catalytic materials with high activity, high stability and low cost.
The polymer semiconductor carbon nitride has moderate band gap, high thermal stability and chemical stability, abundant and cheap raw materials and simple preparation process, and particularly has great application value in the fields of photocatalytic degradation of organic pollutants and photocatalytic water splitting hydrogen production. Carbon nitride has a layered structure similar to graphite with an interlayer spacing of about 0.326nm, slightly less than the interlayer spacing of graphite (0.335 nm). In the structure of the carbon nitride, carbon and nitrogen atoms in the layer are sp 2 Hybridization, inter-phase arrangement, connection into hexagonal aromatic structure similar to benzene ring by sigma bond, connection between rings through terminal nitrogen atom to form infinitely extended planeThe layers are connected by van der Waals forces. The Fuzhou university Wang Xinchen and the like find that the metal-free carbon nitride realizes the decomposition of H under the condition of visible light for the first time 2 O gets H 2 And the band structure of the carbon nitride is researched by a density functional theory and an electrochemical method, so that a forbidden band width of about 2.7eV exists between the highest occupied orbit and the lowest unoccupied orbit, and the carbon nitride has a typical semiconductor band structure. More importantly, the carbon nitride has proper valence band and conduction band positions, and meets the requirement of H 2 O is decomposed into H 2 And O 2 Thermodynamic requirements of Nature Materials, 2009, 8 (1): 76-80. Since then, the novel nonmetallic photocatalytic material is greatly emphasized and studied, and is considered as the photocatalytic material with the highest potential.
However, as a photocatalyst, carbon nitride has some problems such as small specific surface area, high photo-generated carrier recombination rate, low quantum efficiency and large forbidden bandwidth, and only a small part of visible light and the like can be utilized, so that a large distance is left from the aspect of large-scale and efficient utilization of solar energy for water pollution control or photolysis of water to prepare hydrogen. In order to make up for the inherent defect of a single photocatalyst, the method is simple and effective by constructing a carbon nitride-based composite material, can accelerate the separation of photo-generated electrons and holes and prolong the service life of photo-generated carriers, improves the photoelectric conversion efficiency and expands the spectrum absorption range.
The existing research shows that the carbon nano sheet-carbon nano tube composite material has excellent photocatalysis characteristic, and in the photocatalysis process, the carbon nano tube can help to enhance the visible light absorption of the semiconductor photocatalyst, and simultaneously can effectively promote the separation and transfer of photon-generated carriers, and the abundant modification method of the surface of the carbon nano sheet-carbon nano tube composite material also plays an active center role in various catalytic reactions. Qiao Shi of the university of Ardelade synthesizes the carbon nitride nano-sheet/carbon nano-tube composite material (Angewandte Chemie, 2014, 126 (28): 7409-7413.) through electrostatic adsorption and pi-pi stacking strategy, but the carbon nano-tubes synthesized by the method are scattered and distributed on the surface of the carbon nitride nano-sheet, are not firmly combined, and cannot regulate the density of the carbon nano-tubes on the surface of the carbon nitride nano-sheet. Therefore, how to synthesize carbon nanotubes of controlled density in situ on two-dimensional carbon nitride nanoplates is a challenge.
Disclosure of Invention
The invention aims to solve the technical problem of providing a method for in-situ construction of a metal-doped two-dimensional carbon nitride nano sheet/carbon nano tube multi-stage structure and a product thereof, wherein the method has the advantages of stable performance, convenient operation and low cost.
In order to solve the technical problems, the technical scheme of the invention is as follows: the method for in-situ construction of the metal-doped two-dimensional carbon nitride nano sheet/carbon nano tube multi-stage structure is characterized by comprising the following steps:
step one: placing one or more of melamine, melamine hydrobromide, caged phosphate melamine salt and melamine cyanurate into a ceramic or quartz crucible, and performing heat treatment to obtain bulk phase carbon nitride;
step two: carrying out hot etching on the bulk phase carbon nitride obtained in the step one twice to obtain a two-dimensional carbon nitride nano sheet;
step three: uniformly mixing the two-dimensional carbon nitride nano-sheet prepared in the second step with ferric salt, nickel salt, cobalt salt aqueous solution or ethanol solution with a certain concentration, and drying to obtain mixed powder;
step four: placing the mixed powder prepared in the step three in an atmosphere furnace, firstly introducing inert gas to empty oxygen in the mixed powder, then heating up the mixed powder, introducing hydrogen to reduce the mixed powder, and closing the hydrogen after the mixed powder reaches the cracking temperature; introducing inert gas to bring ethanol or methanol into an atmosphere furnace, preserving heat for a period of time, and naturally cooling to room temperature under the atmosphere condition to obtain the metal-doped two-dimensional carbon nitride nano sheet/carbon nano tube multi-stage structure.
The heat treatment temperature in the first step is 540-580 ℃, the heating rate is 5-10 ℃/min, and the heat preservation time is 2-6 h.
The first hot etching temperature in the second step is 500-520 ℃, the heating rate is 10-15 ℃/min, and the heat preservation time is 1-3 h; the temperature of the second hot etching is 540-560 ℃, the temperature rising rate is 10-15 ℃/min, and the heat preservation time is 1-3 h.
The ferric salt in the third step is one of ferric nitrate, ferric chloride, ferric ammonium citrate, ferric stearate, ferric tartrate, ferric ammonium oxalate hydrate, ferrous chloride, ferric phosphate or ferric sulfate; the nickel salt is one of nickel nitrate, nickel chloride, nickel carbonate, nickel stearate, nickel hypophosphite or nickel sulfate; the cobalt salt is one of cobalt nitrate, cobalt chloride, cobalt acetate, cobalt oxalate, cobalt carbonate, cobalt stearate, cobalt phosphate or cobalt sulfate; the mass ratio of the ferric salt, the nickel salt and the cobalt salt to water or ethanol is 1:500.
The mass ratio of the two-dimensional carbon nitride nano-sheet to the ferric salt, the nickel salt and the cobalt salt in the step three is 1:1-10:1.
The hydrogen reduction temperature in the step four is 450-500 ℃, the heating rate is 10-15 ℃/min, the heat preservation time is 1-2 h, and the flow is 30-60 mL/min.
The ethanol or methanol in the fourth step is carried into an atmosphere furnace by nitrogen or argon, the cracking temperature is 480-500 ℃, the heating rate is 10-15 ℃/min, the heat preservation time is 1-2 h, and the flow is 10-80 mL/min.
The metal doped two-dimensional carbon nitride nano sheet/carbon nano tube product prepared by the method is characterized in that: the specific surface area of the product is 352-435 m 2 Per g, the diameter of the carbon nano tube is 18-30 nm, the length of the carbon nano tube is 80-600 nm, and the resistance is 1.8-6 multiplied by 10 3 Ω。
The beneficial effects of the invention are as follows: the preparation of carbon nanotubes by catalytic cracking of ethanol or methanol is a simple process and high yield. The six lone pair electrons of the N atoms in the two-dimensional carbon nitride nanoplates provide near perfect sites for the anchoring of metal ions or atoms. And, because the negatively charged N atoms form strong interactions with metal ions, the two-dimensional carbon nitride nano-sheet can easily capture the metal ions or atoms. Therefore, in the catalytic cracking process, the carbon nano-tube is synthesized by taking the anchored reduced metal particles on the surface of the carbon nitride nano-sheet as a cracking center, so that the carbon nano-tube generated in situ is firmly fixed on the surface of the two-dimensional carbon nitride nano-sheet. By our inventive technique, the following objectives can be achieved: firstly, the ratio of the carbon nitride nano-sheet to the metal salt can be simply regulated and controlled, so that the density of the carbon nano-tube on the surface of the carbon nano-tube can be regulated and controlled. Secondly, the in-situ constructed multi-stage structure feature has extremely low interface resistance, the contact tightness between interfaces is an important factor influencing electron or hole migration, and the tight interface contact can effectively reduce charge transfer resistance, promote charge transmission and improve the separation efficiency of photo-generated electrons and holes, so that the photocatalytic activity of the photocatalyst is improved; thirdly, the multilevel structure often has larger specific surface area, so that the multilevel structure has more abundant catalytic active sites, reaction area and adsorption area to a target object; fourthly, the uniqueness of the multi-stage structure endows the two-dimensional carbon nitride nano-sheet/carbon nano-tube with a multi-level photogenerated carrier transmission and migration channel, which is beneficial to promoting the separation of electrons and holes; fifthly, the carbon nano tubes generated in situ on the two-dimensional carbon nitride nano sheets have the characteristic of directional arrangement, and compared with a mechanically mixed composite photocatalyst, the directional transmission of electrons is endowed, so that the recombination probability of photo-generated electrons and holes is further reduced; and sixthly, in the high-temperature catalytic cracking process, a small part of metal elements can enter into the two-dimensional carbon nitride crystal lattice, so that the electronic structure and the energy band structure of the two-dimensional carbon nitride can be regulated and controlled, and the visible light absorption range is widened.
The invention obtains the metal doped two-dimensional carbon nitride nano-sheet/carbon nano-tube with unique multi-level nano-structure characteristics (two-dimensional/one-dimensional) and large specific surface area (352-435 m) 2 /g), a good microscopic morphology (carbon nanotubes having a diameter of 18 to 30nm and a length of 80 to 600 nm) and a low electrical resistance (1.8X10) 3 ~6×10 3 Ω)。
The method is characterized by comprising the following steps:
a. the raw material sources are rich and the cost is low;
b. the preparation process is simple and efficient, and the operation is simple and convenient;
c. the in-situ construction of the metal-doped two-dimensional carbon nitride nano-plate/carbon nano-tube multi-stage nano-structure is beneficial to providing carrier transmission channels of multiple channels and creating a tightly contacted interface and wide visible light absorption range;
d. the diameter, length and density of the carbon nano tube are easy to regulate and control, and the two-dimensional carbon nitride nano sheet/carbon nano tube multi-level nano structure with different diameters, lengths and densities can be obtained by simply changing the proportion of the salt solution and the two-dimensional carbon nitride nano sheet, the cracking temperature, the cracking time and the like.
Drawings
FIG. 1 is a metal-doped two-dimensional carbon nitride nanoplate/carbon nanotube multi-stage structure after catalytic cracking of example 1;
FIG. 2 is a low magnification scanning electron microscope image of the product obtained in example 1;
FIG. 3 is a high magnification scanning electron microscope image of the product obtained in example 1;
FIG. 4 is a low power transmission electron microscope image of the product obtained in example 1;
FIG. 5 is a high power transmission electron microscope image of the product obtained in example 1.
Detailed Description
The invention will be described in further detail with reference to the drawings and the detailed description.
Example 1
Placing melamine into a ceramic or quartz crucible, placing the ceramic or quartz crucible into a muffle furnace for heat treatment, heating to 540 ℃ at a heating rate of 5 ℃/min, and preserving heat for 4 hours to obtain yellow bulk carbon nitride; grinding the synthesized powder into powder, placing the powder on a ceramic flat plate, spreading the powder as much as possible to enlarge the contact area of the powder and air, and performing hot etching twice, wherein the first hot etching temperature is 500 ℃, the heating rate is 10 ℃/min, and the heat preservation time is 2 hours; cooling and then continuing the second hot etching, wherein the temperature is 540 ℃, the heating rate is 15 ℃/min, and the heat preservation time is 1h, so that the light yellow two-dimensional carbon nitride nano-plate is obtained; then, adding 100mg of two-dimensional carbon nitride nano-sheet into 50g of nickel nitrate aqueous solution with concentration of 0.2wt% for ultrasonic treatment, fully stirring uniformly and drying; then, placing the dried mixed powder in an atmosphere furnace, exhausting oxygen in the furnace, continuously introducing hydrogen at a heating rate of 10 ℃/min and a flow rate of 30mL/min, and closing the hydrogen after the reduction temperature reaches 500 ℃ and the temperature is kept for 2 hours; and carrying ethanol into an atmosphere furnace by inert gas, wherein the flow is 40mL/min, the cracking temperature is 500 ℃, and after heat preservation is carried out for 1h, naturally cooling to room temperature under the atmosphere condition, so as to obtain the nickel-doped two-dimensional carbon nitride nano sheet/carbon nano tube multi-stage structure.
The synthesized nickel-doped two-dimensional carbon nitride nano-plate/carbon nano-tube multi-stage structure is characterized by utilizing a scanning electron microscope and a transmission electron microscope technology, and the diameter of the carbon nano-tube is 18nm, the length of the carbon nano-tube is about 200nm, and the specific surface area of the nickel-doped two-dimensional carbon nitride nano-plate/carbon nano-tube multi-stage structure obtained by a specific surface area tester is 435m 2 And/g, the resistance of the nickel-doped two-dimensional carbon nitride nano sheet/carbon nano tube multi-stage structure is 1.8x10 measured by electrochemical impedance spectroscopy 3 Ω。
FIG. 1 shows the product obtained after catalytic cracking, i.e., the nickel-doped two-dimensional carbon nitride nano-sheet/carbon nano-tube multi-stage structure, which is dark black in color, indicating the formation of carbonaceous material. FIG. 2 is a low-magnification scanning electron microscope photograph of the obtained product, in which a layer of carbon nanotubes grows on the surface of layered two-dimensional carbon nitride, and a large number of nanotubes are crosslinked with each other and are in close contact with the two-dimensional carbon nitride nanoplatelets. FIG. 3 is a high magnification scanning electron micrograph of the resulting product, which further shows that the carbon nanotubes have a relatively uniform size and morphology. FIG. 4 is a low-power transmission electron micrograph of the obtained product, in which a large amount of one-dimensional structural material can be more clearly found in the carbon nitride nano-plate, and FIG. 5 is a high-power transmission electron micrograph of the obtained product, in which the carbon nano-tube with a hollow one-dimensional structure can be clearly observed.
Example 2
Placing melamine into a ceramic or quartz crucible, placing the ceramic or quartz crucible into a muffle furnace for heat treatment, heating to 540 ℃ at a heating rate of 5 ℃/min, and preserving heat for 4 hours to obtain yellow bulk carbon nitride; grinding the synthesized powder into powder, placing the powder on a ceramic flat plate, spreading the powder as much as possible to enlarge the contact area of the powder and air, and performing hot etching twice, wherein the first hot etching temperature is 500 ℃, the heating rate is 10 ℃/min, and the heat preservation time is 2 hours; cooling and then continuing the second hot etching, wherein the temperature is 540 ℃, the heating rate is 15 ℃/min, and the heat preservation time is 1h, so that the light yellow two-dimensional carbon nitride nano-plate is obtained; then, adding 200mg of two-dimensional carbon nitride nano-sheets into 50g of nickel nitrate aqueous solution with the concentration of 0.2wt% for ultrasonic treatment, fully stirring uniformly and drying; then, placing the dried mixed powder in an atmosphere furnace, exhausting oxygen in the furnace, continuously introducing hydrogen at a heating rate of 10 ℃/min and a flow rate of 60mL/min, and closing the hydrogen after the reduction temperature reaches 450 ℃ and the temperature is kept for 1h; carrying ethanol into an atmosphere furnace through inert gas, then naturally cooling to room temperature under the atmosphere condition after the temperature rising rate is 10 ℃/min, the flow is 80mL/min and the cracking temperature is 500 ℃, so as to obtain the nickel-doped two-dimensional carbon nitride nano-sheet/carbon nano-tube multi-stage structure.
The synthesized nickel-doped two-dimensional carbon nitride nano-plate/carbon nano-tube multi-stage structure is characterized by utilizing a scanning electron microscope and a transmission electron microscope technology, and the diameter of the carbon nano-tube is proved to be 30nm, the length of the carbon nano-tube is approximately 600nm, and the specific surface area of the nickel-doped two-dimensional carbon nitride nano-plate/carbon nano-tube multi-stage structure obtained by a specific surface area tester is 410m 2 And/g, the resistance of the nickel-doped two-dimensional carbon nitride nano sheet/carbon nano tube multi-stage structure is 6 multiplied by 10 measured by electrochemical impedance spectroscopy 3 Ω。
Example 3
Placing melamine into a ceramic or quartz crucible, placing the ceramic or quartz crucible into a muffle furnace for heat treatment, heating to 580 ℃ at a heating rate of 10 ℃/min, and preserving heat for 3 hours to obtain yellow bulk carbon nitride; grinding the synthesized powder into powder, placing the powder on a ceramic flat plate, spreading the powder as much as possible to enlarge the contact area of the powder and air, and performing hot etching twice, wherein the first hot etching temperature is 520 ℃, the heating rate is 15 ℃/min, and the heat preservation time is 1h; cooling and then continuing the second hot etching, wherein the temperature is 550 ℃, the heating rate is 15 ℃/min, and the heat preservation time is 2 hours, so that the light yellow two-dimensional carbon nitride nano-plate is obtained; then, adding 1000mg of two-dimensional carbon nitride nano-sheet into 50g of nickel chloride aqueous solution with concentration of 0.2wt% for ultrasonic treatment, fully stirring uniformly and drying; then, placing the dried mixed powder in an atmosphere furnace, exhausting oxygen in the furnace, continuously introducing hydrogen at a heating rate of 10 ℃/min and a flow rate of 60mL/min, and closing the hydrogen after the reduction temperature reaches 480 ℃ and the temperature is kept for 1h; carrying ethanol into an atmosphere furnace through inert gas, then naturally cooling to room temperature under the atmosphere condition after the temperature rising rate is 15 ℃/min, the flow is 40mL/min and the cracking temperature is 500 ℃, so as to obtain the two-dimensional carbon nitride nano sheet/carbon nano tube multi-stage structure.
The synthesized nickel-doped two-dimensional carbon nitride nano-sheet/carbon nano-tube multi-stage structure is characterized by utilizing a scanning electron microscope and a transmission electron microscope technology, and the diameter of the carbon nano-tube is proved to be 25nm, the length of the carbon nano-tube is approximately 100nm, and the specific surface area of the nickel-doped two-dimensional carbon nitride nano-sheet/carbon nano-tube multi-stage structure obtained by a specific surface area tester is 409m 2 And/g, the resistance of the nickel-doped two-dimensional carbon nitride nano sheet/carbon nano tube multi-stage structure is 3.3X10 by electrochemical impedance spectroscopy 3 Ω。
Example 4
Placing melamine into a ceramic or quartz crucible, placing the ceramic or quartz crucible into a muffle furnace for heat treatment, heating to 580 ℃ at a heating rate of 10 ℃/min, and preserving heat for 3 hours to obtain yellow bulk carbon nitride; grinding the synthesized powder into powder, placing the powder on a ceramic flat plate, spreading the powder as much as possible to enlarge the contact area of the powder and air, and performing hot etching twice, wherein the first hot etching temperature is 520 ℃, the heating rate is 15 ℃/min, and the heat preservation time is 1h; cooling and then continuing to carry out the second hot etching, wherein the temperature is 550 ℃, the heating rate is 15 ℃/min, and the heat preservation time is 1h, so as to obtain the light yellow two-dimensional carbon nitride nanosheets; then, adding 200mg of two-dimensional carbon nitride nano-sheets into 50g of 0.2wt% concentration aqueous solution of nitric acid for ultrasonic treatment, fully stirring uniformly and drying; then, placing the dried mixed powder in an atmosphere furnace, exhausting oxygen in the furnace, continuously introducing hydrogen at a heating rate of 10 ℃/min and a flow rate of 40mL/min, and closing the hydrogen after the reduction temperature reaches 500 ℃ and the temperature is kept for 1h; carrying ethanol into an atmosphere furnace through inert gas, then naturally cooling to room temperature under the atmosphere condition after the temperature rising rate is 13 ℃/min, the flow is 40mL/min and the cracking temperature is 500 ℃, so as to obtain the iron-doped two-dimensional carbon nitride nano-sheet/carbon nano-tube multi-stage structure.
The combined iron doped two-dimensional nitriding is performed by utilizing the scanning electron microscope and transmission electron microscope technologyCharacterization of the carbon nano-plate/carbon nano-tube multi-stage structure proves that the diameter of the carbon nano-tube is 28nm, the length of the carbon nano-tube is about 350nm, and the specific surface area of the iron-doped two-dimensional carbon nitride nano-plate/carbon nano-tube multi-stage structure obtained by a specific surface area tester is 360m 2 And/g, the resistance of the iron-doped two-dimensional carbon nitride nano sheet/carbon nano tube multi-stage structure is 2.3 multiplied by 10 measured by electrochemical impedance spectroscopy 3 Ω。
Example 5
Placing melamine into a ceramic or quartz crucible, placing the ceramic or quartz crucible into a muffle furnace for heat treatment, heating to 580 ℃ at a heating rate of 8 ℃/min, and preserving heat for 6 hours to obtain yellow bulk carbon nitride; grinding the synthesized powder into powder, placing the powder on a ceramic flat plate, spreading the powder as much as possible to enlarge the contact area of the powder and air, and performing hot etching twice, wherein the first hot etching temperature is 520 ℃, the heating rate is 10 ℃/min, and the heat preservation time is 1h; cooling and then continuing to carry out the second hot etching, wherein the temperature is 560 ℃, the heating rate is 15 ℃/min, and the heat preservation time is 1h, so as to obtain the light yellow two-dimensional carbon nitride nanosheets; then, adding 800mg of two-dimensional carbon nitride nano-sheet into 50g of 0.2wt% ferric chloride aqueous solution, carrying out ultrasonic treatment, fully stirring uniformly, and drying; then, placing the dried mixed powder in an atmosphere furnace, exhausting oxygen in the furnace, continuously introducing hydrogen at a heating rate of 13 ℃/min and a flow rate of 50mL/min, and closing the hydrogen after the reduction temperature reaches 500 ℃ and the temperature is kept for 1h; and carrying the ethanol into an atmosphere furnace through inert gas, wherein the flow is 60mL/min, the cracking temperature is 500 ℃, and after heat preservation is carried out for 1h, naturally cooling to room temperature under the atmosphere condition, so as to obtain the two-dimensional carbon nitride nano sheet/carbon nano tube multi-stage structure.
The synthesized iron-doped two-dimensional carbon nitride nano-plate/carbon nano-tube multi-stage structure is characterized by utilizing a scanning electron microscope and a transmission electron microscope technology, and the diameter of the carbon nano-tube is 23nm, the length of the carbon nano-tube is about 370nm, and the specific surface area of the iron-doped two-dimensional carbon nitride nano-plate/carbon nano-tube multi-stage structure obtained by a specific surface area tester is 386m 2 And/g, the resistance of the iron-doped two-dimensional carbon nitride nano sheet/carbon nano tube multi-stage structure is 4.1 multiplied by 10 measured by electrochemical impedance spectroscopy 3 Ω。
Example 6
Placing melamine hydrobromide into a ceramic or quartz crucible, placing the crucible into a muffle furnace for heat treatment, heating to 540 ℃ at a heating rate of 10 ℃/min, and preserving heat for 5 hours to obtain yellow bulk carbon nitride; grinding the synthesized powder into powder, placing the powder on a ceramic flat plate, spreading the powder as much as possible to enlarge the contact area of the powder and air, and performing hot etching twice, wherein the first hot etching temperature is 510 ℃, the heating rate is 15 ℃/min, and the heat preservation time is 2 hours; cooling and then continuing to carry out the second hot etching, wherein the temperature is 560 ℃, the heating rate is 15 ℃/min, and the heat preservation time is 1h, so as to obtain the light yellow two-dimensional carbon nitride nanosheets; then, adding 400mg of two-dimensional carbon nitride nano-sheet into 50g of cobalt nitrate ethanol solution with the concentration of 0.2wt% for ultrasonic treatment, fully stirring uniformly and drying; then, placing the dried mixed powder in an atmosphere furnace, exhausting oxygen in the furnace, continuously introducing hydrogen at a heating rate of 13 ℃/min and a flow rate of 50mL/min, and closing the hydrogen after the reduction temperature reaches 500 ℃ and the temperature is kept for 2 hours; and carrying the ethanol into an atmosphere furnace through inert gas, wherein the flow is 70mL/min, the cracking temperature is 500 ℃, and after 2 hours of heat preservation, naturally cooling to room temperature under the atmosphere condition, so as to obtain the two-dimensional carbon nitride nano sheet/carbon nano tube multi-stage structure.
The synthesized cobalt-doped two-dimensional carbon nitride nano-plate/carbon nano-tube multi-stage structure is characterized by utilizing a scanning electron microscope and a transmission electron microscope technology, and the diameter of the carbon nano-tube is proved to be 29nm, the length of the carbon nano-tube is approximately 560nm, and the specific surface area of the cobalt-doped two-dimensional carbon nitride nano-plate/carbon nano-tube multi-stage structure obtained by a specific surface area tester is 432m 2 And/g, the resistance of the cobalt-doped two-dimensional carbon nitride nano sheet/carbon nano tube multi-stage structure is 5.3 multiplied by 10 measured by electrochemical impedance spectroscopy 3 Ω。
Example 7
Placing caged melamine phosphate into a ceramic or quartz crucible, placing the ceramic or quartz crucible into a muffle furnace for heat treatment, heating to 540 ℃ at a heating rate of 8 ℃/min, and preserving heat for 5 hours to obtain yellow bulk carbon nitride; grinding the synthesized powder into powder, placing the powder on a ceramic flat plate, spreading the powder as much as possible to enlarge the contact area of the powder and air, and performing hot etching twice, wherein the first hot etching temperature is 500 ℃, the heating rate is 10 ℃/min, and the heat preservation time is 2 hours; cooling and then continuing the second hot etching, wherein the temperature is 540 ℃, the heating rate is 15 ℃/min, and the heat preservation time is 1h, so that the light yellow two-dimensional carbon nitride nano-plate is obtained; then, adding 500mg of two-dimensional carbon nitride nano-sheet into 50g of nickel sulfate aqueous solution with concentration of 0.2wt% for ultrasonic treatment, fully stirring uniformly and drying; then, placing the dried mixed powder in an atmosphere furnace, exhausting oxygen in the furnace, continuously introducing hydrogen at a heating rate of 15 ℃/min and a flow rate of 60mL/min, and closing the hydrogen after the reduction temperature reaches 500 ℃ and the temperature is kept for 2 hours; and carrying the ethanol into an atmosphere furnace through inert gas, wherein the flow is 70mL/min, the cracking temperature is 500 ℃, and after heat preservation is carried out for 1h, naturally cooling to room temperature under the atmosphere condition, so as to obtain the nickel-doped two-dimensional carbon nitride nano sheet/carbon nano tube multi-stage structure.
The synthesized nickel-doped two-dimensional carbon nitride nano-plate/carbon nano-tube multi-stage structure is characterized by utilizing a scanning electron microscope and a transmission electron microscope technology, and the diameter of the carbon nano-tube is 24nm, the length of the carbon nano-tube is about 358nm, and the specific surface area of the nickel-doped two-dimensional carbon nitride nano-plate/carbon nano-tube multi-stage structure obtained by a specific surface area tester is 400m 2 And/g, the resistance of the nickel-doped two-dimensional carbon nitride nano sheet/carbon nano tube multi-stage structure is 4.6X10 by electrochemical impedance spectroscopy 3 Ω。
Example 8
Placing melamine cyanurate into a ceramic or quartz crucible, placing the crucible into a muffle furnace for heat treatment, heating to 550 ℃ at a heating rate of 5 ℃/min, and preserving heat for 4 hours to obtain yellow bulk carbon nitride; grinding the synthesized powder into powder, placing the powder on a ceramic flat plate, spreading the powder as much as possible to enlarge the contact area of the powder and air, and performing hot etching twice, wherein the first hot etching temperature is 500 ℃, the heating rate is 10 ℃/min, and the heat preservation time is 1h; cooling and then continuing the second hot etching, wherein the temperature is 540 ℃, the heating rate is 15 ℃/min, and the heat preservation time is 1h, so that the light yellow two-dimensional carbon nitride nano-plate is obtained; then, adding 100mg of two-dimensional carbon nitride nano-sheets into 50g of ferric nitrate ethanol solution with the concentration of 0.2 weight percent, carrying out ultrasonic treatment, fully stirring uniformly, and drying; then, placing the dried mixed powder in an atmosphere furnace, exhausting oxygen in the furnace, continuously introducing hydrogen at a heating rate of 10 ℃/min and a flow rate of 50mL/min, and closing the hydrogen after the reduction temperature reaches 500 ℃ and the temperature is kept for 2 hours; and carrying the ethanol into an atmosphere furnace through inert gas, wherein the flow is 60mL/min, the cracking temperature is 500 ℃, and after heat preservation is carried out for 1h, naturally cooling to room temperature under the atmosphere condition, so as to obtain the iron-doped two-dimensional carbon nitride nano sheet/carbon nano tube multi-stage structure.
The synthesized iron-doped two-dimensional carbon nitride nano-plate/carbon nano-tube multi-stage structure is characterized by utilizing a scanning electron microscope and a transmission electron microscope technology, and the diameter of the carbon nano-tube is 22nm, the length of the carbon nano-tube is about 480nm, and the specific surface area of the iron-doped two-dimensional carbon nitride nano-plate/carbon nano-tube multi-stage structure obtained by a specific surface area tester is 390m 2 And/g, the resistance of the iron-doped two-dimensional carbon nitride nano sheet/carbon nano tube multi-stage structure is 2.6X10 measured by electrochemical impedance spectroscopy 3 Ω。
Example 9
Placing melamine and melamine hydrobromide into a ceramic or quartz crucible, placing the ceramic or quartz crucible into a muffle furnace for heat treatment, heating to 540 ℃ at a heating rate of 5 ℃/min, and preserving heat for 4 hours to obtain yellow bulk carbon nitride; grinding the synthesized powder into powder, placing the powder on a ceramic flat plate, spreading the powder as much as possible to enlarge the contact area of the powder and air, and performing hot etching twice, wherein the first hot etching temperature is 500 ℃, the heating rate is 15 ℃/min, and the heat preservation time is 1h; cooling and then continuing the second hot etching, wherein the temperature is 540 ℃, the heating rate is 10 ℃/min, and the heat preservation time is 1h, so that the light yellow two-dimensional carbon nitride nano-plate is obtained; then, adding 100mg of two-dimensional carbon nitride nano-sheet into 50g of nickel nitrate aqueous solution with concentration of 0.2wt% for ultrasonic treatment, fully stirring uniformly and drying; then, placing the dried mixed powder in an atmosphere furnace, exhausting oxygen in the furnace, continuously introducing hydrogen at a heating rate of 10 ℃/min and a flow rate of 30mL/min, and closing the hydrogen after the reduction temperature reaches 500 ℃ and the temperature is kept for 2 hours; and carrying the ethanol into an atmosphere furnace through inert gas, wherein the flow is 20mL/min, the cracking temperature is 500 ℃, and after heat preservation is carried out for 1h, naturally cooling to room temperature under the atmosphere condition, so as to obtain the nickel-doped two-dimensional carbon nitride nano sheet/carbon nano tube multi-stage structure.
The synthesized nickel-doped two-dimensional carbon nitride nano-plate/carbon nano-tube multi-stage structure is characterized by utilizing a scanning electron microscope and a transmission electron microscope technology, and the diameter of the carbon nano-tube is 21nm, the length of the carbon nano-tube is approximately 261nm, and the specific surface area of the nickel-doped two-dimensional carbon nitride nano-plate/carbon nano-tube multi-stage structure obtained by a specific surface area measuring instrument is 426m 2 And/g, the resistance of the nickel-doped two-dimensional carbon nitride nano sheet/carbon nano tube multi-stage structure is 2.0x10 measured by electrochemical impedance spectroscopy 3 Ω。
The above-described embodiments are merely illustrative of the principles and functions of the present invention, and some of the practical examples, not intended to limit the invention; it should be noted that modifications and improvements can be made by those skilled in the art without departing from the inventive concept, and these are all within the scope of the present invention.

Claims (8)

1. The method for in-situ construction of the metal-doped two-dimensional carbon nitride nano sheet/carbon nano tube multi-stage structure is characterized by comprising the following steps:
step one: placing one or more of melamine, melamine hydrobromide, caged phosphate melamine salt and melamine cyanurate into a ceramic or quartz crucible, and performing heat treatment to obtain bulk phase carbon nitride;
step two: carrying out hot etching on the bulk phase carbon nitride obtained in the step one twice to obtain a two-dimensional carbon nitride nano sheet;
step three: uniformly mixing the two-dimensional carbon nitride nano-sheet prepared in the second step with ferric salt, nickel salt, cobalt salt aqueous solution or ethanol solution with a certain concentration, and drying to obtain mixed powder;
step four: placing the mixed powder prepared in the step three in an atmosphere furnace, firstly introducing inert gas to empty oxygen in the mixed powder, then heating up the mixed powder, introducing hydrogen to reduce the mixed powder, and closing the hydrogen after the mixed powder reaches the cracking temperature; introducing inert gas to bring ethanol or methanol into an atmosphere furnace, preserving heat for a period of time, and naturally cooling to room temperature under the atmosphere condition to obtain the metal-doped two-dimensional carbon nitride nano sheet/carbon nano tube multi-stage structure.
2. The method according to claim 1, characterized in that: the heat treatment temperature in the first step is 540-580 ℃, the heating rate is 5-10 ℃/min, and the heat preservation time is 2-6 h.
3. The method according to claim 1, characterized in that: the first hot etching temperature in the second step is 500-520 ℃, the heating rate is 10-15 ℃/min, and the heat preservation time is 1-3 h; the temperature of the second hot etching is 540-560 ℃, the temperature rising rate is 10-15 ℃/min, and the heat preservation time is 1-3 h.
4. The method according to claim 1, characterized in that: the ferric salt in the third step is one of ferric nitrate, ferric chloride, ferric ammonium citrate, ferric stearate, ferric tartrate, ferric ammonium oxalate hydrate, ferrous chloride, ferric phosphate or ferric sulfate; the nickel salt is one of nickel nitrate, nickel chloride, nickel carbonate, nickel stearate, nickel hypophosphite or nickel sulfate; the cobalt salt is one of cobalt nitrate, cobalt chloride, cobalt acetate, cobalt oxalate, cobalt carbonate, cobalt stearate, cobalt phosphate or cobalt sulfate; the mass ratio of the ferric salt, the nickel salt and the cobalt salt to water or ethanol is 1:500.
5. The method according to claim 1, characterized in that: the mass ratio of the two-dimensional carbon nitride nano-sheet to the ferric salt, the nickel salt and the cobalt salt in the step three is 1:1-10:1.
6. The method according to claim 1, characterized in that: the hydrogen reduction temperature in the step four is 450-500 ℃, the heating rate is 10-15 ℃/min, the heat preservation time is 1-2 h, and the flow is 30-60 mL/min.
7. The method according to claim 1, wherein the ethanol or methanol in the fourth step is carried into an atmosphere furnace by nitrogen or argon, the cracking temperature is 480-500 ℃, the heating rate is 10-15 ℃/min, the heat preservation time is 1-2 h, and the flow is 10-80 mL/min.
8. The metal-doped two-dimensional carbon nitride nanoplatelets/carbon nanotubes article made by the method of claim 1, wherein: the specific surface area of the product is 352-435 m 2 Per g, the diameter of the carbon nano tube is 18-30 nm, the length of the carbon nano tube is 80-600 nm, and the resistance is 1.8-6 multiplied by 10 3 Ω。
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